1. Field of the Invention
The present invention relates to a safety device for vehicle, and more particularly to an inflatable air-belt for a vehicle safety system.
2. Description of the Prior Art
A conventional safety belt for vehicle usually consists of a simple fibrous strip and is designed to limit the forward motion of the upper half of the occupant. The above-mentioned safety belt functions to prevent fatal accident by keeping the occupant from moving forward and striking the vehicle structure during a collision. However, since the safety belt restrains the occupant with its simple narrow fibrous bend as mentioned above, the safety belt may rapidly apply intense pressure to the breast and the abdominal regions of the occupant. Hence, the breast and the abdominal regions of the occupants may be intensely wounded as a result of application of the rapid pressure.
on the other hand, safety belt of air bag type (so called "air-belt") which is adapted to be inflated in a very short time by introducing gas from an air tank thereinto when a shock power by collision of the vehicle is higher than a predetermined value are disclosed in U.S. Pat. Nos. 3,866,940 and 3,865,398.
However, since the safety belt of air bag type has inflatable sections made of soft flexible PVC material, etc., which is normally exposed, the inflatable sections of the belt is liable to be damaged. On the other hand, if the inflatable sections are made of hard material in order to overcome the abovementioned problem occurring in the soft PVC air-belt, occupant concern about damage to his chest and abdomen area, due to belt tightening, decreases but since the air-belt does not have much capability of inflating, due to the hard material used, the shock absorption is not enough to prevent injuries caused by an accident. Accordingly, it is not desirable that the material of the air-belt made of hard material. However, the soft material of the air-belt is substantially expensive. In case of the former air-belt, since the air-belt is constructed of two separate sections, it is complicated in structure. Also, since the two section of the air-belt have fixed lengths, it is difficult to adjust length of the air-belt to a size of the occupant.
In case of the latter air-belt, although the air-belt is designed to substantially solve the problem of the former by providing an L-shaped traveler having a foot sliding along a rod, it is required to have additional complicated components such as the rod, an end mount and the L-shaped traveler and thus the components occupy considerable space to be mounted in the vehicle. Hence, the air-belt is not desirable from an appearance point of view because of the additional components. And if a middle buckle in the latter is secured to a vehicle body, the breast and the abdominal region can be protected against collision by means of a single air-belt. However, the middle buckle has a serious problem in that since a hole of an elongated ring of the middle buckle is relatively small, inflating gas pressure which has inflated the lower part of the air -belt below the middle buckle can not immediately inflate the upper part of the air-belt due to a portion of the belt fastened by the middle buckle, thereby causing the complete inflation to be retarded. In order to solve the problem in that the air-belt is fastened by the middle buckle, it is desirable that the hole of the elongated ring is four times or larger than the sectional area of the air-belt. But it is not suitable in appearance and also another article may be caught in the middle buckle.
Furthermore, since the air-belts of the both types are drooped when not in use, it is not comfortable to wear them and their appearance is not attractive.